dankaar already talked about most of your mechanical errors, and this thing is decently written, so I'd just recommend that you look it over a couple more times to catch any stray grammatical mistakes. Most of your mistakes are in clunky, awkward syntax. For example…

After 19 minutes, D-1339 attacked and destroyed the two-way mirror from behind which the Foundation researchers observed him

This is a very unwieldy clause. "After 19 minutes, D-1339 attacked and destroyed the observational two-way mirror" works a lot better, because you don't have to juggle dumb prepositional phrases.

and attempted self-strangulation with it

why not just "and attempted to strangle himself with it," because "self-strangulation" is pretty awkward?

Anyway, on the content of your article: you're right, your idea definitely needs a lot of rethinking. I think that it would be more productive to you to think about re-writing what you have instead of adding on more content to make it work. Ideally, your article should be one cohesive whole, so tacking on new stuff onto stuff that was written without the old stuff in mind generally shows; the new stuff just seems underdeveloped. Instead of adding working decoration to a broken foundation, it's better to fix the foundation.

I'm going to second dankaar's question as the fundamental problem with your article: "Why should I care about these paints?" You want to make me care in some way, by scaring me or intriguing me or whatever. Like, if I feel something, then your article means something to me. Right now, your article makes me feel nothing.

Right now, I think one of the easiest ways to brainstorm a fix to your idea is that your article as-is is just begging the question: who the hell made these things, and why? What if you were to write and characterize a person who made these paints, and you gave this person a motivation as to why they did so? There are obviously other ways you can go about this, but if I were tasked with fixing this, that's what I would do.

Do you think it would work as something from Dr. Wondertainment? With some changes to the article itself, of course. Also, I was thinking about a cross test with SCP-753. Something about using those paints affecting what 753 produces, maybe it could temporarily allay its suicidal-ness.

#1: Shoehorning a GOI in almost never improves an article, and more often than not, lowers its quality. If you want to do something with a GOI, its better to build the SCP around the specific GOI.

#2: Crosslinking is almost never done now, as it is excessively hard to pull off well. Articles that do pull it off well almost never actually require the crosslink to make it better. Also, as 753 is at about +150, you'll face additional problems as it looks like you're trying yo leech upvotes.

I'm not sure about this, mainly because colors aren't really consistently tied to certain emotions across cultures. For example, some East Asian countries view white as a color of mourning, and red as a lucky color that would be worn to weddings or special occasions. A good example of such differences is this handy picture. Additionally, a quick internet search would bring up several informational pages, including this one.